But to make his case, Cockburn dispenses with proportion and distinction. Though in successive reports the U.N., Amnesty International and Human Rights Watch have indicted the Assad regime as by far the leading perpetrator of violence in the conflict, Cockburn’s account is devoted almost entirely to opposition atrocities. (He reports exclusively from regime-held areas.) Regime repression does receive cursory mention, but Nazi analogies are reserved for the opposition.

Cockburn makes no mention of the divergent interests and active rivalries between IS and Syria’s nationalist opposition. For him, to assist the opposition is to assist the IS.

To support this claim, he quotes “an intelligence officer from a Middle Eastern country neighboring Syria” who told him “ISIS members ‘say they are always pleased when sophisticated weapons are sent to anti-Assad groups of any kind because they can always get the arms off them by threats of force or cash payments.’” (Cockburn quotes many anonymous intelligence officials in the book but on no other occasion does he grant the country anonymity. Might it be because the “country neighboring Syria” is Iraq, a key Assad ally?)

Yet this bias is the least of the problems in Cockburn's reporting—he also embellishes. On page 76 of his book, he writes about Adra: “I witnessed JAN forces storm a housing complex by advancing through a drainage pipe which came out behind government lines, where they proceeded to kill Alawites and Christians.” This would be the first independent verification of a story that had briefly surfaced before disappearing in a swirl of contradictory claims. The Russian broadcaster RT had even used fake pictures in its report on the incident.

Yet Cockburn was nowhere near Adra. This is confirmed by an unimpeachable source: Patrick Cockburn. He first reported on the incident in his January 28, 2014 column for The Independent. But instead of being personally present, the story about rebels advancing through a drainage pipe is attributed to “a Syrian soldier, who gave his name as Abu Ali.” Cockburn appears to have pulled a Brian Williams."